岡山大学工学部
Acta Medica Okayama
0475-0071
21
1
1986
Dynamic Behavior of Sand Bed around Structure under Wave Motion
81
91
EN
10.18926/15836
Under the attack of storm waves, there are many destructions of coastal structures due to scouring, sinking and sliding. These types of destructions are
considered to be in close relation to the dynamic behavior of sand bed around the structures. In this study the characteristics of pore water pressure and stresses in the sand bed around a breakwater under the attack of superposed waves are treated theoretically. The results show that during the crest or the trough being in front of the structure the strength of sand bed around the structure decreases notably and the unstable zone will occur.
No potential conflict of interest relevant to this article was reported.
岡山大学工学部
Acta Medica Okayama
0475-0071
21
1
1986
Determination of Coefficients of Groundwater Flow in Multilayered Aquifers
71
79
EN
10.18926/15835
It is difficult to determine the coefficients of groundwater flow from the data which were obtained from the
drawdown test in a multiaquifer system. In this paper, new methods of analyzing drawdown-tests are developed and illustrated with the example to determine aquifer coefficients. In a double-layered aquifer, the analytical solution of drawdown test, in which water is discharged from both layers, is derived. And also the theoretical solution to determine the coefficient of storage by using an index of elasticity of a confined aquifer is derived.
From these solutions, methods of determining the coefficient of transmissibility in a double-layered aquifer
and the coefficinent of storage in a confined aquifer are
got. The example analysis to determine aquifer coefficients
is shown. As a result, the characteristics which were
obtained by these methods are verified by the real drawdown
test data.
No potential conflict of interest relevant to this article was reported.
岡山大学工学部
Acta Medica Okayama
0475-0071
21
1
1986
Prediction of Shrinkage and Creep of Concrete
57
70
EN
10.18926/15832
New prediction equations of shrinkage and creep of concrete are proposed, and the efficiency of the new
equations are investigated through a number of experimental
data. Furthermore,the characteristics and applications of the prediction equations presented in the codes of many countries are also discussed. The results showing that the new equations could estimate shrinkage and creep of concrete within a certain measure of accuracy were obtained.
No potential conflict of interest relevant to this article was reported.
岡山大学工学部
Acta Medica Okayama
0475-0071
21
1
1986
Charge Density Fluctuation in Ionic Mixtures
45
55
EN
10.18926/15831
The total charge fluctuation spectrum of ionic mixtures is analyzed on the basis of the solution of the hypernetted-chain equation for the binary ionic mixtures. A simple but sufficiently accurate scaling law in the domain of intermediate coupling is obtained and the result is applied to the calculation of the bremsstrahlung emission and absorption rates in high density plasmas composed of ions of many species.
No potential conflict of interest relevant to this article was reported.
岡山大学工学部
Acta Medica Okayama
0475-0071
21
1
1986
Surface Properties of Classical One-Component Plasma
31
43
EN
10.18926/15830
Surface properties of classical one-component plasma are investigated by numerical experiments on the system with periodicity in two directions perpendicular to the planar surface. The density profile, the electrostatic potential, the electric field, and the surface energy are obtained for intermediate values of the coupling parameter of bulk part r and compared with earlier experiments on spherical system. For r=10, the surface energy is almost the same as earlier result. For r =1, however, the surface energy is
reduced about a factor of 2. The consistency of experimental values of the potential with the exact relation is checked and necessity of large system size is pointed out.
No potential conflict of interest relevant to this article was reported.
岡山大学工学部
Acta Medica Okayama
0475-0071
21
1
1986
A Computer Program of Assembly Line Balancing Considering the Performance Rate of Each Work Station
17
30
EN
10.18926/15829
Assembly line balancing is to assign work elements to serial work stations so as to make the work content at each station as close as possible to one limiting cycle time or pitch time, i.e., an upper time limit over every station. Until now, it is usually assumed that the
performance rates of work stations are constant. But in
practice the performance abilities of workers, machines or robots are varied by their own working conditions. Then the actual station times are different from standard ones, and consequently the line balance may diminish in many cases. Therefore in this paper, we propose an improved
balancing method, in which work elements can be assigned to the work station having the upper time limit changed by its performance rate or ability. Further we develop the computer program of the proposed method and provide an illustrative problem and computational results. In an application of our method to the practical problems, it is shown that the actual efficiency of the production line becomes near that planned.
No potential conflict of interest relevant to this article was reported.
岡山大学工学部
Acta Medica Okayama
0475-0071
21
1
1986
Analysis of Brushless-dc Motor Drive System Taking Account of a Load
1
16
EN
10.18926/15827
In the power converter of ac drive system the switching behavior of semiconductors causes the distorted voltage and current waveforms, thus the drive characteristics are affected by them. It is, especially, an essential problem that the distorted current waveforms induce the torque ripple. It is assumed in the previous analysis that the input voltage of inverter is a ripple-free dc one. In industry, however, the input voltage of inverter is gained by rectifying the ac voltage. The torque ripple is caused by not only the behavior of inverter but also the behavior of converter. It is required to develop the analysis taking account of the both behaviors. In this paper, the analysis of brushless-dc motor drive system is proposed taking account of the ac supply, power converter, motor and load. This analytical method is the most suitable one for the analysis of practical system. The effects of factors, e.g. filter constants, inverter frequency, phase
relation between ac supply and inverter cycle, load and inertia on the speed variation are revealed by this analysis. Further, the decision of filter constants is
discussed from a view of speed variation.
No potential conflict of interest relevant to this article was reported.